Bicycle



(No Model'.)

C. H. METZ.

BIGYGLE. 9 No. 513,589. Patented Jan. 30, 1894.

STATE PATENT Erich.

CHARLES H. METZ, OF HIGHLANDVILLE, ASSIGNOR TO THE UNION CYCLE MANUFACTURING COMPANY, OF BOSTON, MASSACHUSETTS.

BICYCLE.

SPECIFICATION forming part of Letters Patent No. 513,589, dated January 30, 1894.

Application filed November 19, 1892- Serial No. 452,528| (No model.)

To all whom it may concern:

Be it known that I, CHARLES H. METZ, of Ilighlandville, in the county of Norfolk, State of Massachusetts, have invented certain new and useful Improvements in Bicycles, of which the following is a description sufficiently full, clear, and exact to enable any person skilled in the art or science to which said invention appertains to make and use the dicate corresponding parts in the different figures of the drawings.

In bicycles and similar crank-actuated vehicles where an elliptical sprocket is employed on the crank-shaft for actuating the drive-wheel the tension of the jack-chain connecting the sprocket-wheels varies at different points in the revolution of the elliptical sprocket; as, for example, when the majoraxis of the sprocket is vertical the chain is tighter than when the minor-axis is in this position. adjust the chain on the sprockets when the major-axis is at right-angles to the plane passing through the crank-shaft and axis of the drive wheel. Many objectionable features attend the loosening of the chain during a portion of the revolution of the elliptical sprocket and my invention is designed especially to overcome this by so mounting the elliptical sprocket that the tension of the chain shall be at all times equal.

In the drawings, A represents the body of the bicycle which in its principal features is of the ordinary form and construction. Aportion only of the drive-wheel and frame is shown it being deemed all that is necessary to illustrate my device. The sprocket, b, is mounted on the axle of the wheel in the usual manner. The crank-axle, d, is journaled in For this reason it is necessary to the frame in the ordinary way and the elliptical sprocket-wheel, m, is mounted thereon. The hub of said wheel is slotted at right-angles to the major-axis of the ellipse to receive the crank-shaft. A rectangular opening, f, shown in the diagram in Fig. 2 is thus formed. The axle, d, is squared at CV, to enter said opening which in breadth tightly fits said squared portion. The sprocket, m, is thus mounted to slide laterally of its shaft.

To ascertain the requisite length to cutthe crank-opening in the ellipse a line, '0, (see Fig. 2) is struck through the center of the ellipse when the major-axis is at right-angles to the plane of the sprocket-shafts indicated by line, 11 in Fig. 2. Tangent lines, 12 and, p are then drawn, connecting the circle representing the sprocket, b, with the ellipse, m. A line, o vertical to the plane, U is struck through the center of the sprocket, b, and its point, '0 of intersection with the tangent, 41 is taken as a center, and with the distance from said point to the intersection of the tangent, o, with the line, 11, as a radius, an are, 0 is struck.

The sprocket, m, is represented by dotted lines with its major-axis in the plane, o At the point, c of intersection of the are, '0 with said sprocket a line, n is drawn parallel with the line, '0, and coinciding with the minor axial line. The distance between these lines, o, "0 indicates the variation in the length of the tangents, c and, 11 from the tangents, 22 and, o or the distance it is requisite to permit the elliptical sprocket to move laterally of its shaft, when rotating, from the position represented by dotted lines in the diagram to that shown by the full lines. These tangents represent the jack-chain.

In fitting the chain to the sprockets when the ordinary fixed center is used it is neces sary to adjust the same thereon when the minor-axis of the ellipse is in the plane, '0 as at such point the tangent lines are longer by the distance between the lines, o, 0?, than when the ellipse is in position with its minoraxis at right-angles to such plane. The slot, f, is cut in length to exceed the side of the square, (1 by a distance double the distance between the lines, 0, c This enables the sprocket to move on its journal as the position of its major-axis changes holding the chain, B, at all times at the same tension. The journal of the sprocket being squared to receive it and fitted to slide tightly in the slot, f, the space, f, is divided equally at opposite sides of the journal when the majoraxis is in the plane, '0 as indicated by the diagram, changing therefrom as said axis of revolution.

Any means other than that described may be employed for moving the elli ptical-sp rocket laterally of the drive-shaft without departing from the spirit of my invention, the primary feature of which comprises so adjusting or mounting an elliptical drive-sprocket connecting with a circular sprocket on a fixed center that it may automatically move laterally of the drive-shaft and compensate for the variation in the tension of the chain. Moreover it is not essential that the sprocket be mounted on the crank-axle as in geared machines it may be on an intermediate shaft.

My deviceis also applicable for use in mechanism other than bicycles or similar vehicles as it may be employed in all cases where a variable speed is obtained by the use of an elliptical pulley, wheel or sprocket.

In Fig. 4 of the drawings an alternative method is shown for mounting the elliptical sprocket on the shaft. In this form an arm, 2, is fast by an end on the shaft, d The sprocket, m has no spokes. Said sprocket near one end of its major-axis is pivoted at, y, to the outer end of the arm, z, a head being formed on said arm for this purpose.

On said head at opposite sides of the pivot there are notches or projections, 15, which are engaged by pins or projections, 16, on the rim of the sprocket-wheel. The sprocket is thus pivoted to swing a limited distance laterally of its shaft, (1 Such distance, determined by the position of the pins, is ascertained in the same manner as that described for the slotted sprocket.

Instead of one arm, .2, another arm arranged diametrically opposite to the arm, 2, and fast on the shaft may be employed, if desired, for strength. The resultant from this construction is identical with that of the slotted sprocket.

Having thus explained my invention, what I claim is- 1. The combination with a rotary-shaft, of an elliptical wheel or sprocket mounted thereon to move laterally thereof, substantially as and for the purpose set forth.

2. An elliptical drive-sprocket provided with a rectangular shaft-openingin combination with a crank-shaft squared to enter said opening said squared portion being of less diameter in one direction than the diameter of said shaft-opening in the corresponding direction.

3. In a bicycle or similar vehicle the combination of a crank-shaft, an elliptical sprocket mounted thereon and adapted to movelaterally thereof, a drive-wheel; a sprocket on the axle of said wheel and a chain connect ing said sprockets.

4. In a bicycle, the combination of a crankshaft provided with a portion square in crosssection, of an elliptical sprocket having a rectangular shaft-opening for receiving the squared portion of said crank-shaft the diameter of said opening being greater in one direction than the corresponding diameter of said shaft; a drive-wheel; a sprocket on the axle of said wheel; and a chain connecting said sprockets substantially as setforth.

CHARLES H. METZ. Witnesses:

O. M. SHAW, K. DURFEE. 

